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Discharging and Recharging a Car’s AC System

Discharging and Recharging a Car's AC System

You are driving down the streets of your city on a beautiful summer day. You are enjoying your favorite tunes on the radio when suddenly you feel usually hot. You realize there is something wrong with your car's air conditioning system. You look to see if your car is leaking refrigerant, but it is not. You curse to yourself thinking of the hefty bill you are likely to receive from your mechanic.

Auto Repairs Are EXPENSIVE


Before taking your car to the mechanic, you may want to try evacuating and recharging your air conditioning system yourself. It is probably simpler than you think it is and it can save you a lot of money.


an AC system works by removing heat rather than adding cold. It does this by using a system of air circulation that includes a compressor and a condenser. It uses a refrigerant, which absorbs heat. An AC system may go bad if there is a low level of refrigerant. 

Understanding Your Car’s AC System

Your car’s AC system is made up of seven components. It employs a closed-loop format and runs refrigerant throughout. 

  1. The Compressor: This component is powered by a belt-drive and pulls in cold gas refrigerant. It then turns the refrigerant hot. It pumps the refrigerant through the AC system. When it leaves the compressor, the pressurized refrigerant goes into the high-pressure tubing and into the condenser. 


  1. The Condenser: The condenser causes the gas refrigerant to turn into a liquid refrigerant. The air travels through the condenser and cools down the hot refrigerant. It also removes heat from the air conditioning. The refrigerant will then cool into a liquid. The refrigerant will then travel to the receiver/dryer.


  1. The Receiver/dryer: This is a reservoir that’s job is to remove moisture from the AC system. If moisture gets into the system, it might damage an AC system’s components if it freezes.


  1. The Thermal Expansion Valve/orifice tube: Between the dryer and evaporator you will find a valve that limits the flow of the liquid refrigerant and dampers its temperature. This makes the refrigerant expand and the pressure to lower.


  1.  The Evaporator: This component is located under the car’s dash. Cool low-pressure refrigerant comes into the evaporator and becomes a gas as it absorbs heat from the cabin. 


  1. The Refrigerant: The refrigerant used in automotive AC systems is called R134a, or 1,1,1,2-tetrafluoroethane. It is a gas with a boiling point of 15 degrees below zero. This boiling point rises under pressure and condenses into a liquid.


  1. The Accumulator: You will find the accumulator between the evaporator and the condenser. It acts as a system filter and helps get rid of water and refrigerant.


You should know that air conditioning evacuation requires that your car has no leaks for the procedure to be effective. If there are leaks, check the valve hoses and connections. If the connections are bad or the wrong type of hose has been used, you will need to replace the bad hose before proceeding with the discharge.


 You will need a few simple tools to start the discharging process. If you do not have these tools, you can rent them or buy them from any automotive store or hardware store. You may even be able to find them in the hardware section of your local Walmart.

Tools You Will Need

  • Manifold air gauges
  • Vacuum pump
  • Auto repair manual
  • Rags


Auto air conditioning systems must be evacuated as part of the vehicle’s regular upkeep. The AC system will need to be recharged as well. Automakers use a wide variety of AC systems and parts. All AC systems have the same basic function and have a similar design.  


Here are the basic discharging instructions:


  1. Attach the manifold air gauges. 

You will want to consult your owner’s manual to find the location of your car’s AC valves. Manifold air gauges have two gauges. They also have three hoses, one of them is red, one is yellow and the other is blue. The red hose will connect to the high-pressure valve and the blue hose attaches to the low-pressure valve. The low-pressure valve is also known as the suction valve.


You will find the high-pressure valves located on the receiver/dryer bottle which is connected to the compressor. You will find the low-pressure valve below and in front of the receiver/dryer bottle. 

  1. Connect the Yellow Line to the Vacuum Pump

 Once the yellow line is attached, close the high and low gauges by turning the red and blue knobs. You will then want to start the vacuum pump. You will be able to find instructions for starting it in your owner’s manual.


  1. Open the High and Low-Pressure Valves on the Air Gauge. 

When you look at the air gauge the blue side should show a vacuum, which reads at, or below zero. If it is not at zero, your AC system may have a leak. 


If the vacuum does read zero, run the pump for thirty minutes. You should then turn the pump off and close the red and blue gauges. The evacuation of your automobile air conditioning system is now complete and you are ready to begin recharging it.


You will only need half an hour to recharge your ac and even a beginner can do it. It’s very important to do the repair safely and legally.


Safety First

Always be careful when you are working with cans of compressed air. Never leave the cans in the sun because if it gets too hot it could explode. It is a violation of environmental laws to spray refrigerant into the air.


Tools You Will Require

You will need a few things to recharge your AC

  1. Can of refrigerant
  2. Hose connector, if it is not included with the refrigerant.
  3. Safety Goggles
  4. Gloves


As with all car repairs, you will need a flat workspace to recharge your AC.  Work in a garage with the door open if you can.


  1. Turn the ignition on and put the car in park, and put the parking brake on.
  2. Turn the AC and the fans up to their highest setting, and press the button that recirculates the air.
  3. Open the hood, and locate the AC low-pressure service port between the compressor and the evaporator, and take off the cap. Your owner’s manual can help you locate it if you have trouble. 
  4. Disconnect the attachment hose from the can of refrigerant and then connect the hose to the low-pressure point.
  5. While the compressor is cycling, look at the included gauge and turn the temperature dial to the current temperature.
  6. Do not continue with the recharge, if the pressure reading is in the red section of the gauge. This could mean the compressor is malfunctioning. 
  7. If the PSI reads lower than “full” on the gauge, you need to add refrigerant. 
  8. Take the hose off the service port. 
  9. Take the safety tab off of the can of refrigerant. shake the can up and reattach the gauge and the hose to the can.
  10. Attach the hose to the low-pressure service port.
  11.  Use the trigger to start recharging the system with the refrigerant. Move the can up and down so the refrigerant flows smoothly.
  12. Use the gauge to determine when the system is full. It is very important not to overcharge the system.
  13. Detach the connector from the port.
  14. Recycle the empty cans of refrigerant.


If you do not have a safe place to work on your car or if you are an apartment dweller, you may want to take your car to a mechanic for a recharge. A mechanic will charge an average of $150 to recharge your AC.


If you need to have leaks fixed in your air conditioning system, it will cost anywhere from $150 to $800. If you need to replace an air conditioning system, it can cost up to $4000. 


If you do decide to go to a mechanic for AC repair or replacement, you will have a couple of options as to where to take your vehicle.


Taking Your Car to an Auto Body Shop

Auto body shops are far and away the most popular option for car repairs in America. They will not charge you nearly as much as the dealership will and you will be able to speak with the mechanic directly. 


It is important to select a reputable auto body shop. You can find a list of approved auto body shops on the AAA website. They list shops all over the country on their site. 


Be sure to ask the mechanic about his or her training and get an estimate of the repairs in writing. You should also ask for references.


Taking Your Car to The Dealership

A dealership mechanic is likely to charge you two or three times as much for labor as an auto body shop mechanic would. However, a dealership mechanic will be specifically trained in your make and model of car. The dealership will also be able to rent you a car while they work on your air conditioning. They will charge you by the job and not the hour so there will be no surprises when you get your final bill.


An air conditioning system is extremely expensive to repair or replace. If your car needs a new air conditioning system, it may be time for a new vehicle. If you buy a new automobile you will have several options as to where to sell your old one.


You can use the car as a trade-in. When you buy your new car, the dealership will offer you a certain amount of money for a trade-in allowance. They will not offer you what your old car is really worth because they know you want everything to be convenient and to get the purchase of your new car over with quickly. 


They may even try to tack the money they gave you for the trade-in back onto the final price of the new car. You should read your paperwork very carefully before signing in. 


It may be a good idea not to mention that you have a trade-in at all. Get a final price for the new car and then tell them that you have a trade-in.


You can also try to sell your car online. There are many websites that will let you list your vehicle for a monthly fee. It may take several months to sell your car this way. 


When you do get an interested buyer, you will have to take time out of your day to show them the car. They may decide not to buy it or they may decide that you are asking too much for it. You can take what they offer you or continue to look for another buyer.


Sell Your Car to Us

Cash Cars Buyers has a very easy system for getting rid of a used car. Just fill out our form and we will call you back with an offer. We ask for your contact information and the make, model, year, VIN number, and mileage of your vehicle.  


If you sell your car to an individual or if you use it as a trade-in, you will have to have the pink slip. In most cases, we don't need the title, just your license, and registration.


If you accept the offer that we make you, we will make an appointment to come and pick up your car. We will pay you in cash and tow the old vehicle away for free. It really is that simple. 

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